assetHistory(string Name, int Mode): int

Parameters:

Returns:

Remarks:

• Price history is stored in the History folder under Name plus .t6 extension for D1 data, or Name plus .t1 for T1 data. The file name can be modified with the History string. T1 or M1 data downloaded from a broker is split into separate years, EOD data or data from an online source is stored in a single file. The Quandl database name, an appended ".US" by Stooq, and '/', '.', or ':' characters are automatically stripped from the historical data file names. If the name is otherwise different to the asset name, use file_copy to copy the downloaded file to the correct asset name (f.i. file_copy("History\\ICE.t6","History\\LONDONICE.t6").
• Price history is only downloaded in the INITRUN and only when the existing price history is not already up to date. For this the most recent online price is compared with the history file date, and if the difference is less than 12 hours, no new history is downloaded. For downloading data after the INITRUN and regardless of existing history, use either the OVERRIDE flag or the dataDownload function.
• When downloading data from a broker, the asset is subscribed automatically (if possible via API). The recent values of the asset's Spread, PipCost, etc. are updated to the Assets.csv file even if no price history is downloaded. This way new assets can be added and available assets can be set up to their current parameter values for further simulations.
• Price history from the broker is downloaded either for the number of recent years given by NumYears, or for all years between StartDate and EndDate. If NumYears is set to -1, no data is downloaded, but the Assets.csv list is still updated. Price history from online sources is normally downloaded for a fixed number of years depending on the source.
• Price data from a broker or from some online sources (IEX, Cryptocompare) is appended at the begin of an existing data file. Price data from other sources is not appended, but replaces the previous file. For this, make sure that the time resolution of the downloaded prices matches the resolution of the historical data files - normally, 1 minute (M1 data). EOD or D1 price data (1 day resolution) is stored in a single .t6 file per asset that can go back until 1990.
• For backtesting price history, BarPeriod can not be less than one price history bar. Set it to 1440 for testing D1 price data. For testing only parts of a multi-year .t6 file, use an 8-digit StartDate or EndDate.
• The raw .csv data from websites (Google, Quandl, etc) is stored in History\history.csv. If the price source does not deliver price data, but some error message instead, a "Bad file format" error is displayed, and the error message is then contained in the downloaded History\history.csv file. The function will attempt twice to download the data before giving up.
• Check the correct spelling of the asset name or code. Spelling often differs slightly, f.i. the same stock can be named BRK.B, BRK_B, BRK-B, or BRK-B.US dependent on the website or price source.
• Outliers in the price history are automatically fixed on download dependent on the Outlier variable.
• A price history file with length 0 prevents downloading prices for that particular year. This way, by storing a 0-byte file, price data that is not available or that is of bad quality can be excluded from download attempts and from the backtest.
• Download price history before calling asset(), otherwise the asset will use the existing price data files. Use UpdateDays for calling assetHistory automatically to keep the price history up to date.
• For T1 data, the price server of the broker must support quote-based price data; this is the case for FXCM, but not for Oanda, IB, or MT4(MT5 brokers. Dependent on the price server speed, downloading T1 prices can take a long time, such as a whole day for one year of price quotes. If the LEAN flag is not set, ask and bid prices are stored in the .t1 file, otherwise only ask prices. 
• For trading with brokers that do not support historical prices in their API at all, set the PRELOAD flag and use assetHistory() for downloading recent historical data prior to the first asset call. This works for D1 data only.
• Adjusted prices can be split-adjusted, dividend-adjusted, or both. For short-term trading backtests is split-adjustment the best choice, for long-term trading dividend- and split-adjustment. But since dividend adjustment has little effect on short-term backtests, you normally use dividend- and split-adjusted prices for all backtests.
• Some comments about the online data sources (all trademarks are property of their owners):
  • Google prices are adjusted for splits only, unadjusted prices are not available. Google download is known to fail on certain assets for no apparent reason, even though they can be downloaded manually. The service was recently not available.
  • Yahoo data is loaded in an 'inofficial' way (don't tell them!). Prices are split and dividend adjusted; UNADJUSTED prices are still split adjusted. Yahoo EOD data was reported to contain 2 entries on dividend payment days, one with the current and one with previous day's data. Yahoo data of some European assets could be of poor quality; check the resulting price curve if in doubt.
  • AlphaVantage data loads relatively slow when there is much traffic. The data has good quality. UNADJUSTED is supported. The AV API key must be present in Zorro.ini.
  • Stooq requires a currency identifier appended to stock or ETF names. If it is missing, ".US" is automatically appended. The data loads fast and is of good quality. UNADJUSTED is supported. There is a limit to the number of downloads per day, identified through the IP address.
  • Quandl data from the WIKI (stocks), CHRIS/CME and CHRIS/ICE (futures), BITFINEX and GDAX (Bitcoin and other cryptocurrencies) EOD databases are supported. Quandl databases in different formats can be downloaded with the dataDownload function. Quandl data loads fast and has usually good quality. The Quandl key must be present in Zorro.ini and the asset's database code (f.i. "WIKI/AAPL" or "BITFINEX/ETHBTC") must be passed to Name.
  • IEX provides EOD data for US equities. UNADJUSTED is supported; otherwise data is split, but not dividend adjusted. Since the data amount is limited, Zorro compares the current date with the file date of an existing history file and downloads as few data as possible. The IEX API token must be present in Zorro.ini.
  • Bittrex provides recent price history for a large number of cryptocurrencies. Format: BTC-ETH returns ETH prices in BTC. The history length is normally several years for D1 data, several months for H1 data, and several days for M1 data. It is recommended to insert a 4 seconds delay between subsequent loadHistory calls.
• CryptoCompare provides recent price history for almost all existing cryptocurrencies. Format: ETH/BTC returns ETH prices in BTC. The history length is up to 3 years for D1 data, 1 year for H1 data, and 1 month for M1 data. Due to the limited length, Zorro attempts to merge downloaded data with prior data present in the History folder. If this is not desired, delete the older data or use the OVERRIDE flag. Since digital currencies are not traded at a central exchange, CryptoCompare prices can be slightly different to the Bittrex prices.
• MT4/MT5 servers usually have no long price history, so the command will print an error message or only partially download the history.
• IB market data must be subscribed before it can be downloading. For downloading stock M1 data, send a SET_PRICETYPE,2 command for switching to the last traded price, because ask/bid prices are sometimes in poor quality.
• FCXM servers provide tick price history from 2002 for currencies, and from 2008 for index CFDs.
• Before downloading prices, check if they are already available in the History folder or on the Zorro download page. M1 and options EOD data for US stocks can also be purchased from oP group.

Example:

// Update M1 price history of all assets
function run()
{
  NumYears = 2;
  while(loop(Assets))
    assetHistory(Loop1,1);
  quit();
}

// Download D1 prices from Quandl
function run()
{
  ...
  string Name;
  while(Name = loop("AAPL","MSFT","GOOGL")) {
    assetHistory(strf("WIKI/%s",Name),FROM_QUANDL);
    asset(Name);
    ...
  }
  ...
}

// Download and plot Bitcoin prices from Bitfinex
function run()
{
  BarPeriod = 1440;
  assetHistory("BITFINEX/BTCUSD",FROM_QUANDL);
  assetAdd("BTCUSD");
  asset("BTCUSD");
  set(PLOTNOW);
}

See also: